1-Methyl-, 3-methyl-, 8-methyl-, 1, 3-dimethyl-, 7, 10-methyl-, and 8, 9-dimethylfluoranthene were synthesized and their NMR spectra recorded. The results show double bonds in the positions: 2, 3-, and 4, 5-which are equivalent to the fixed double bond in 9, 10-position in phenanthrene. There is a high degree of double bond character in 8, 9-position. The electronic spectra of fluoranthene, 2, 3-benzo-fluoranthene, naphtho [2′: 3′, 2: 3] ...